Reduce PDF file size : free Acrobat replacement for Leopard

Hi Yannis.

I am not sure if this is related to OS X 10.8 and I have no way to check, since all my Macs are running 10.8.2.

I remember the filters being increaisng the size for some converidsions (as reported by some in thi discusiion) but never had any particular problem sinc OS X Mountain Lion.

However, yesterday (after seing your post :-) I exported a 1.8 MB file (that was the concatenation of a scanned page and 5 other pages from an already file-size-reduced PDF) using the "standard compression" and had a 8.2 MB as a result.

Even stranger, exporting the 8.2 MB file using the same standard settings resulted in a 2.7 MB file !

And those results were consistent after reboot and several retries.

But everything still works fine with a nice file size reduction for other files.

I guess this is an OS X bug : the filters themselves are very simple Colorsync filters (you should be able to see them in Colorsync Utility) which apply 3 Apple-provided filters for image sampling (1 filter for color ; 1 filter for B&W) and 1 filter for jpeg compression.

However I am not an expert and have not found an easy way to analyze the PDF files and check for image resolution or jpeg compression.

(I am an Adobe CS6 subscriber but did not find anything useful for that in Acrobat Pro)

So if anyone knew of a tool to check for the properties of objects in a PDF, preferably working on Macs, that would be great!.

Hi Yiannis.

There are actually (very well hidden) PDF analyzing features in Acrobat Pro.

So I now have a solution for larger than the original result files, that you have reported (and other users of these filters have reported too) later in that post.

But first the cause for these two large files: for some (unknown by me) reason, the images within the target files are not JPEG-compressed.

It looks like a bug to me, so I am going to file a bug report with Apple right away.

And here is the solution: re-export the target file with a filter only enabling JPEG-compression for images within the PDF.

Here is this filter: Click here to download.

It is the same as the standard compression filter "Reduce to 150 dpi average quality - STANDARD COMPRESSION" but without the dpi settings and seems to work well for me.

Just put it next to the other filters in "Macintosh HD/Library/PDF Services" if your startup disk is called "Macintosh HD" and choose it in preview when re-exporting to PDF the too large files produced by the previous pass.

Yiannis, does this work for you?

Hi Dannymac22.

Those filters only care for images. They have no interest for PDFs which are mostly text; And in the case of an optimized PDF they will not help.

But they will help for (most of) the non compressed PDFs produced by OS X's printing or scanning.

As to the WHY, I cared a lot about it and if you re-read my last post, it is because JPEG compression is not applied although it should.

Hi Dannymac22.

If you're interested in knowing why (small caps are nicer :-) a PDF export from Preview can produce a bigger file than the orginal, you are probably not at the right place.

However, to give you a flew clues, you can certainly easily understand that OS X's handling of PDF hasnot been optimized for file size optimization only (for example, speed is of the essence). And it seems that PDF export by Preview are not "pass through" exports, especially when you apply filters. During the export, Preview undoes previous optimizations and applies its own, possibly not as efficient from a file size standpoint.

This discussion as about an easy way to reduce the size of user created PDFs (through printing or scanning especially) without needing expensive or unintuitive tools like Acrobat Pro, which was not even available on Leopard when this discussion started.

And the "why" we wanted to understand is why these filters failed miserably in some cases although they work well most of the times.

Luckily, I think we have an answer, and, better yet, a solution :-)

Hope I could help a bit